[PATCH] powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU

[PATCH] powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU

[Haren Myneni]

The hypervisor assigns VAS (Virtual Accelerator Switchboard)
windows depends on cores configured in LPAR. The kernel uses
OF reconfig notifier to reconfig VAS windows for DLPAR CPU event.
In the case of shared CPU mode partition, the hypervisor assigns
VAS windows depends on CPU entitled capacity, not based on vcpus.
When the user changes CPU entitled capacity for the partition,
drmgr uses /proc/ppc64/lparcfg interface to notify the kernel.

This patch adds the following changes to update VAS resources
for shared mode:
- Call vas reconfig windows from lparcfg_write()
- Ignore reconfig changes in the VAS notifier

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/lparcfg.c | 15 ++++++++
 arch/powerpc/platforms/pseries/vas.c     | 44 ++++++++++++++++--------
 arch/powerpc/platforms/pseries/vas.h     |  5 +++
 3 files changed, 50 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index 507dc0b5987d..23f9c96e9abc 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -35,6 +35,7 @@
 #include <asm/drmem.h>
 
 #include "pseries.h"
+#include "vas.h"	/* pseries_vas_dlpar_cpu() */
 
 /*
  * This isn't a module but we expose that to userspace
@@ -748,6 +749,20 @@ static ssize_t lparcfg_write(struct file *file, const char __user * buf,
 			return -EINVAL;
 
 		retval = update_ppp(new_entitled_ptr, NULL);
+
+		if (retval == H_SUCCESS || retval == H_CONSTRAINED) {
+			/*
+			 * The hypervisor assigns VAS resources based
+			 * on entitled capacity for shared mode.
+			 * Reconfig VAS windows based on DLPAR CPU events.
+			 * Returns success, -EIO, -EINVAL, or -ENOMEM
+			 */
+			retval = pseries_vas_dlpar_cpu();
+			if (!retval)
+				retval = count;
+
+			return retval;
+		}
 	} else if (!strcmp(kbuf, "capacity_weight")) {
 		char *endp;
 		*new_weight_ptr = (u8) simple_strtoul(tmp, &endp, 10);
diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 93f87ac126df..bf15586f2af7 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -857,6 +857,26 @@ int vas_reconfig_capabilties(u8 type, int new_nr_creds)
 	mutex_unlock(&vas_pseries_mutex);
 	return rc;
 }
+
+int pseries_vas_dlpar_cpu(void)
+{
+	int new_nr_creds, rc = 0;
+
+	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
+					vascaps[VAS_GZIP_DEF_FEAT_TYPE].feat,
+					(u64)virt_to_phys(&hv_cop_caps));
+	if (!rc) {
+		new_nr_creds = be16_to_cpu(hv_cop_caps.target_lpar_creds);
+		rc = vas_reconfig_capabilties(VAS_GZIP_DEF_FEAT_TYPE,
+						new_nr_creds);
+	}
+
+	if (rc)
+		pr_err("Failed reconfig VAS capabilities with DLPAR\n");
+
+	return rc;
+}
+
 /*
  * Total number of default credits available (target_credits)
  * in LPAR depends on number of cores configured. It varies based on
@@ -871,7 +891,15 @@ static int pseries_vas_notifier(struct notifier_block *nb,
 	struct of_reconfig_data *rd = data;
 	struct device_node *dn = rd->dn;
 	const __be32 *intserv = NULL;
-	int new_nr_creds, len, rc = 0;
+	int len;
+
+	/*
+	 * For shared CPU partition, the hypervisor assigns total credits
+	 * based on entitled core capacity. So updating VAS windows will
+	 * be called from lparcfg_write().
+	 */
+	if (is_shared_processor())
+		return NOTIFY_OK;
 
 	if ((action == OF_RECONFIG_ATTACH_NODE) ||
 		(action == OF_RECONFIG_DETACH_NODE))
@@ -883,19 +911,7 @@ static int pseries_vas_notifier(struct notifier_block *nb,
 	if (!intserv)
 		return NOTIFY_OK;
 
-	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
-					vascaps[VAS_GZIP_DEF_FEAT_TYPE].feat,
-					(u64)virt_to_phys(&hv_cop_caps));
-	if (!rc) {
-		new_nr_creds = be16_to_cpu(hv_cop_caps.target_lpar_creds);
-		rc = vas_reconfig_capabilties(VAS_GZIP_DEF_FEAT_TYPE,
-						new_nr_creds);
-	}
-
-	if (rc)
-		pr_err("Failed reconfig VAS capabilities with DLPAR\n");
-
-	return rc;
+	return pseries_vas_dlpar_cpu();
 }
 
 static struct notifier_block pseries_vas_nb = {
diff --git a/arch/powerpc/platforms/pseries/vas.h b/arch/powerpc/platforms/pseries/vas.h
index a2cb12a31c17..7115043ec488 100644
--- a/arch/powerpc/platforms/pseries/vas.h
+++ b/arch/powerpc/platforms/pseries/vas.h
@@ -141,10 +141,15 @@ int __init sysfs_pseries_vas_init(struct vas_all_caps *vas_caps);
 
 #ifdef CONFIG_PPC_VAS
 int vas_migration_handler(int action);
+int pseries_vas_dlpar_cpu(void);
 #else
 static inline int vas_migration_handler(int action)
 {
 	return 0;
 }
+static inline int pseries_vas_dlpar_cpu(void)
+{
+	return 0;
+}
 #endif
 #endif /* _VAS_H */
-- 
2.26.3

Re: [PATCH] powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU

[Michael Ellerman]

On Thu, 06 Oct 2022 22:29:59 -0700, Haren Myneni wrote:
> The hypervisor assigns VAS (Virtual Accelerator Switchboard)
> windows depends on cores configured in LPAR. The kernel uses
> OF reconfig notifier to reconfig VAS windows for DLPAR CPU event.
> In the case of shared CPU mode partition, the hypervisor assigns
> VAS windows depends on CPU entitled capacity, not based on vcpus.
> When the user changes CPU entitled capacity for the partition,
> drmgr uses /proc/ppc64/lparcfg interface to notify the kernel.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU
      https://git.kernel.org/powerpc/c/2147783d6bf0b7ca14c72a25527dc5135bd17f65

cheers